1. Field of the Invention
The present invention relates to a photoelectronic device and the production method and, particularly, relates to a photoelectronic device configured that a light emitting element for emitting a light to be a clock signal is optically connected to a semiconductor chip having an electron circuit including a light receiving portion by an optical waveguide sheet, and the production method.
2. Description of the Related Art
Demands for portable electronic apparatuses, such as a digital video camera, a digital cellular phone and a notebook personal computer, to be more compact, thinner and lighter have only become stronger and, to respond thereto, a reduction in size by 70% has attained in a VLSI and other semiconductor devices in three years.
On the other hand, a package form of semiconductor devices has also developed from a lead-inserted type, such as a DIP (Dual Inline Package), to a surface mounting type and a flip-chip mounting type, furthermore, to a complex form called a system-in-package (SIP), wherein a semiconductor chip provided with an active element is packaged with a passive element.
As explained above, development of semiconductor techniques is remarkable, and particularly in the field of a CPU and high-speed logic LSI, the clock frequency has already exceeded GHz order.
Wiring of a signal exceeding GHz suffers from a lot of disadvantages to be solved inside and outside the LSI, which have not been any problems before, and solution of these disadvantages is a very significant element in recent semiconductors becoming furthermore higher in integration and higher in speed.
The disadvantages are signal distortion (signal integrity), a frequency limit of electric wiring, a loss of wiring, delay of wiring, radiation from wiring, a signal skew, and an increase of power consumption relating to driving wiring, etc.
Particularly, in recent years, a skew (timing difference) of a clock to be supplied in an LSI chip or to different LSIs has become a problem. For example, time of 1 digit of 1 GHz is 500 ps, and time of rising and falling is about several 10 ps to 200 ps or shorter, while in wiring on a general dielectric, wherein ∈=4 or so, a rough propagation speed of an electric signal is 67 ps/cm, which has reached an unignorable range with respect to the rising time.
Thus, lots of attempts have been made to suppress a wiring skew by using completely equal-length wiring also for wiring on a mounting substrate or on an LSI, and dividing a clock to wiring having an H-shape called an H bar to suppress a wiring skew.
When performing clock dividing by electric wiring of the related art, there was a disadvantage that a power consumption became large because a wiring load was always driven by a clock frequency, furthermore, waveform shaping was performed at each dividing point.
To overcome the above disadvantages, instead of electric wiring using a metal, such as aluminum and copper, there is a proposal of using optics for wiring and dividing a clock.
For example, the non-patent article (Shiou Lin Sam, Anantha Chandrakasan and Duane Boning, Variation Issues in On-Chip Optical Clock Distribution, Sixth International Workshop on Statistical Methodologies for IC Processes, Devices, and Circuits, Kyoto, Japan, June 2001) discloses a technique of obtaining a wiring plate having an optical clock tree by forming an optical waveguide on a silicon substrate and processing the same by using a mask in a semiconductor process for each LSI.
However, in the above method of forming clock wiring layers successively by a semiconductor process on a substrate, such as silicon, ceramic or an organic substrate, there is a trouble that design and a mask corresponding to a specific LSI have to be made and processing has to be performed for that each time.
Also, since all production processes are performed sequentially, the entire TAT (turn around time) becomes long and it is hard to deal with small changes.